Improve linenoise and get it working on Windows

Some progress has been made on introducing completion but there's been
difficulties using the Python C API to get local shell variables.

libc/calls/readansi.c

@@ -102,6 +102,7 @@ ssize_t readansi(int fd, char *buf, size_t size) {
         break;
       case kCsi:
         switch (c) {
+          case '[':
           case ':':
           case ';':
           case '<':